Many companies make what's known as conversion lenses that you can screw onto the front of your camcorder. You have to get the right size, of course, and it is best used outdoors, since it is counter to the wider angles preferred indoors. Conversion lenses have different powers, but the best application for yours is probably the 2X, which would effectively give you 40X zooming.
Keep in mind that as soon as you screw it on, your "normal" view for close in shots will have doubled. I personally probably wouldn't put a conversion lens on the DCR DVD 92, since its zoom is already fairly capable. But since I'm opting for a camera with better quality CCD sensors and therefore better video, and since such cameras so far only go to 10X zoom because of engineering constraints with those larger CCD's, I will get a 2X conversion lens for my outdoor videos when I buy my hoped-for DCR DVD 505. Your built-in 20X zoom would certainly be easier than screwing a lens on and off as circumstances change from close-in to far-away, but I also get additional protection for the Carl Zeiss lens from the extra one I add, although a UV filter lens would also provide that protection.
Lots of stores sell the conversion lenses, and, as usual, aftermarket lenses are cheaper. Sony makes them, and I think they have different qualities to choose from - you get what you pay for, so to preserve whatever video quality you already have, you should try to research for the best conversion lens you can afford. I didn't see them on their website, but I know Ritz Camera (Wolfe Camera) has them in their stores. Personal experience and online research has taught me that they are high priced but they provide fantastic customer service and have the most knowledgeable staff. To peruse lenses online, go to Best Buy's site, I think under camcorders and accessories, lenses; you should find all kinds of conversion lenses. I'm not saying to buy there necessarily, should take a look at some options. You might look at CompUSA and Circuit City as well, and their stores may have them on display.